Device for maintaining a developability regulating apparatus contaminant free

Abstract

A device in which a developability regulating apparatus employed in a multi-color electrophotographic printing machine is maintained substantially free from contaminating particles. This is achieved in the present invention by directing a substantially laminar fluid flow over the light source and photosensor used in the developability apparatus.

What is claimed is: 
     
       1. A multicolor electrophotographic printing machine of the type having a photoconductive drum for recording successive single color electrostatic latent images which are rendered viewable by a development apparatus adapted to deposit toner particles complementary in color thereon, and a developability regulating apparatus comprising a light source arranged to illuminate an electrode mounted on the photoconductive drum and electrically biased to a voltage level sufficient to attract toner particles thereto during the development of the latent image and a photosensor for detecting the intensity of the light rays reflected from the electrode to indicate the density of the toner particles deposited thereon, wherein the improvement includes: a first tubular shell arranged to support the light source therein, said first tubular shell having inlet and outlet apertures therein with the light source positioned in the region of the inlet aperture to produce light rays directed outwardly from the light source through the outlet aperture of said first tubular shell to the electrode;   first means, in communication with said first tubular shells, for creating a fluid flow in said first tubular shell, directed from the inlet aperture to the outlet aperture thereof;   a second tubular shell having one end portion thereof integral with said first tubular shell in the region of the outlet aperture and the other end portion thereof flared in an outwardly direction to maintain substantially laminar fluid flow in said first tubular shell to prevent the accumulation of contaminating deposits on the light source;   a housing arranged to support the photosensor therein, said housing having inlet and outlet apertures therein with the photosensor positioned in the region of the inlet aperture thereof to detect the intensity of light rays transmitted inwardly to the photosensor from the electrode;   means in communication with said housing for creating a fluid flow in said housing directed from the inlet aperture to the outlet aperture thereof and   means, associated with said housing for maintaining the fluid flow in said housing substantially laminar to prevent the accumulation of contaminating deposits on the photosensor.   
     
     
       2. A multicolor electrophotographic printing machine of the type having a photoconductive drum for recording successive single color elecrostatic latent images which are rendered viewable by a development apparatus adapted to deposit toner particles complementary in color thereon, and a developability regulating apparatus comprising a light source arranged to illuminate an electrode mounted on the photoconductive drum and electrically biased to a voltage level sufficient to attract toner particles thereto during the development of the latent image and a photosensor for detecting the intensity of the light rays reflected from the electrode to indicate the density of the toner particles deposited thereon, wherein the improvement includes; a housing arranged to support the light source therein, said housing having inlet and outlet apertures therein with the light source positioned in the region of the inlet aperture to produce light rays directed outwardly from the light source through the outlet aperture of said housing to the elecrode;   means, in communication with said housing for creating a fluid flow in said housing directed from the inlet aperture to the outlet aperture thereof;   means, associated with said housing for maintaining the fluid flow in said housing substantially laminar to prevent the accumulation of contaminating deposits on the light source;   a first tubular shell arranged to support the photosensor therein, said first tubular shell having inlet and outlet apertures therein with the photosensor positioned in the region of the inlet aperture thereof to detect the intensity of light rays transmitted inwardly to the photosensor from the electrode;   means, in communication with said tubular shell, for creating a fluid flow in said first tubular shell directed from the inlet aperture to the outlet aperture thereof; and   a second tubular shell having one end portion thereof integral with said first tubular shell in the region of the outlet aperture thereof and the other end portion thereof flared in an outwardly direction to maintain substantially laminar fluid flow to prevent the accumulation of accumulation of particles on the photosensor.